Oxide products formed from calcined carbonate powder for use as biocide, chemical detoxifier and catalyst support products

Abstract

A process and apparatus for manufacture of oxide products for use as biocide, chemical detoxifying, and catalytic support products, from caustic calcined carbonate powder, preferably from magnesite, dolomite, or hydromagnesite, is described. These oxide particles are characterized by high surface area, high porosity and a high degree of calcination, and the method of manufacture utilizes an indirectly heated counterflow reactor. The oxides may be used as a powder, granules, or formulated into a slurry and used as a spray, emulsion, foam or fog, or the powder product may be directly applied. Also described is the formation of particles with microstructures defined by at least one nano-crystalline structure positioned on the outer surface of the particles.

The claims defining the invention are as follows: 
     
       1. A process for producing a biocide powder or a chemical detoxifier powder or a catalyst support from a carbonate compound, comprising the steps of:
 a) grinding the mineral to produce a powder with a broad particle size distribution in the range of 1-100 microns, with a mean particle size of 10-20 microns; 
 b) calcining the powder in an externally heated counterflow flash calciner to produce an oxide with a high surface area, high porosity, and a high degree of calcination; 
 c) forming a stable, readily thinned, slurry of the hydrated oxide with about 60% solids in the final product after hydration, by the process of mixing the powder with water, under conditions in which the temperature is maintained at or near the boiling point of water until the hydration is completed, shear mixing is applied, and a carboxylic acid or salt is added as the thinning agent; 
 d) quenching the slurry to below 60° C.; 
 e) cooling the slurry to ambient temperature; and 
 f) adding additives to enhance the biocidal properties. 
 
     
     
       2. The process of  claim 1 , wherein the carbonate compound is magnesite, with a surface area of the oxide being greater than 150 m 2 /gm, with the degree of calcination being preferably greater than 90%. 
     
     
       3. The process of  claim 1 , wherein the carbonate compound is dolomite, wherein the degree of calcination is set to produce semidolime MgO.CaCO 3 , with a surface area greater than 30 m 2 /gm. 
     
     
       4. The process of  claim 1 , wherein the carbonate compound is a magnesium hydrocarbonate, and the degree of calcination is set to produce magnesium oxide MgO, with a surface area greater than 230 m 2 /gm. 
     
     
       5. The process of  claim 1 , wherein the carboxylic acid is acetic acid, and the carboxylic salt is magnesium or calcium acetate. 
     
     
       6. The process of  claim 1 , wherein the additive is an aqueous solution of hydrogen peroxide. 
     
     
       7. The process of  claim 1 , wherein the additive is ozone, which is sparged into the slurry. 
     
     
       8. The process of  claim 1 , wherein the additive is a dispersant. 
     
     
       9. The process of  claim 1 , wherein the slurry or powder is used to produce a spray, or mixed with oil to form an emulsion, or processed into a foam or fog. 
     
     
       10. A reaction apparatus for producing a biocide powder or a chemical detoxifier powder or a catalyst support from a carbonate mineral, comprising:
 a. a grinder for carbonate minerals; 
 b. an externally heated counterflow flash calciner that produces high surface area oxides from the ground carbonate; 
 c. a second reaction vessel having an inlet for caustic calcined carbonate powder and a water inlet; 
 d. a shearing apparatus for shearing the reaction mixture; 
 e. a steam outlet for release of steam from the reaction vessel, such that, in use, the reaction is controlled by allowing heat of hydration to raise the temperature of the reaction mixture, allowing water to boil off from the reaction mixture as hydration proceeds, and removing steam via the steam outlet to remove excess heat and control the reaction temperature at a boiling point; 
 f. a means of quenching the slurry to below 60° C.; 
 g. a means of cooling the slurry to ambient temperature; 
 h. a means of adding solid or liquid additives to the slurry; and 
 i. a means of sparging the slurry with ozone. 
 
     
     
       11. A chemical composition adapted for use as a biocide, comprising:
 a sprayable slurry of particles of calcined carbonate powder suspended in water, wherein the particles have a porosity of greater than 0.5 and wherein the surface of the particles includes microstructures defined by at least one nano-crystalline structure positioned on the outer surface of the particles. 
 
     
     
       12. The chemical composition of  claim 11 , wherein the carbonate powder is magnesite. 
     
     
       13. The chemical composition of  claim 12 , wherein the particles are adapted to allow the microstructures to be released from the surface of each particle over a predefined time interval. 
     
     
       14. The chemical composition of  claim 13 , wherein the particles form nano-particles adapted to provide a high redox potential. 
     
     
       15. The process of  claim 2 , wherein the surface area of the oxide is greater than 190 m 2 /gm. 
     
     
       16. The process of  claim 2 , wherein the additive is a dispersant. 
     
     
       17. The process of  claim 3 , wherein the additive is a dispersant. 
     
     
       18. The process of  claim 2 , wherein the slurry or powder is used to produce a spray, or mixed with oil to form an emulsion, or processed into a foam or fog. 
     
     
       19. The process of  claim 3 , wherein the slurry or powder is used to produce a spray, or mixed with oil to form an emulsion, or processed into a foam or fog. 
     
     
       20. The process of  claim 4 , wherein the slurry or powder is used to produce a spray, or mixed with oil to form an emulsion, or processed into a foam or fog.